This page contains excerpts from web-pages by Craig Rusbult, Ph.D.
•
The Science of a "Chemical Evolution" Origin of Life (short, medium, long,
plus other views)
• The Second Law of Thermodynamics and "Chemical Evolution" for the
Origin of Life
• METHODOLOGICAL Questions
about "Origin
of Life" Science and
Intelligent Design
• PHILOSOPHICAL Questions about "Origin of Life"
Science
and Methodological Naturalism
• a LINKS-PAGE (written by me as editor trying to describe a wide range of views accurately, not as
an author arguing for my own views)
about The Origin of Life: Abiogenesis by Chemical Evolution?
The Science
of Chemical Evolution (short version)
In an attempt to explain
the origin of life, scientists propose a two-stage process of natural chemical
evolution:
1) formation of organic molecules,
which combine to make larger biomolecules;
2) self-organization of these molecules
into a living organism.
For each stage, scientists are
learning that what is required for life seems to be
much greater than what is possible by natural
process. This huge difference has motivated scientists to creatively
construct new theories for reducing requirements and enhancing possibilities,
but none of these ideas
has progressed from speculation to plausibility.
The simplest "living system" we can imagine, involving hundreds of components interacting in an organized way to achieve energy production and self-replication, would be extremely difficult to assemble by undirected natural process. And all of this self-organization would have to occur before natural selection (which depends on self-replication) was available.
Basically, the Second Law of Thermodynamics
is just a description of probability, ... stating that during
any reaction the entropy of the universe will increase. ...
The everyday analogies used by some
young-earth creationists — like "a tidy room becoming messy" due
to increasing entropy — are not used in scientific applications of the
Second Law, because entropy is about energy distributions and associated probabilities,
not macroscopic disorder, and our psychological intuitions
about "entropy as disorder" are often wrong. ...
Living organisms in the earth's biosystem are maintained in their unusual state (having high chemical potential energy, with low constraint-entropy and normal temperature-entropy) by using external energy from the sun, with solar energy first being directly consumed by plants, which convert it into chemical potential energy that can be consumed by animals. In both plants and animals, coordinated biological systems produce the mechanisms of life — operating in control systems, coupled reactions, and in many other ways — that are necessary to make these unusual things happen.
Now we'll look at "problems
to solve" in a formation of life by Chemical Evolution:
1) an evolutionary mechanism [mutation-and-selection] would not exist before
life began,
2) and neither would the coordinated biological systems that make unusual things
happen,
3) including the formation of specific biomolecules that are needed to make
the systems;
4) some chemical reactions that seem important for life are energetically unfavorable.
As
you read the comments below, think about how each of the four problems involves
a
"chicken and egg" relationship, if life is necessary
to produce what is necessary for life.
1) The origin of life requires a minimal complexity that may exceed what can be produced by natural process, and until a system can accurately reproduce itself (until it's alive?) the neo-Darwinian evolutionary mechanisms cannot help a system (or a population of systems) move toward the minimal complexity that is required for life.
2) A wide variety of biological processes, ...
Thaxton & Bradley "conclude
that, given the availability of energy and an appropriate coupling mechanism,
the maintenance of a living system far from equilibrium presents no thermodynamic
problems." But they recognize the important difference
between maintenance and origin: "While the maintenance of
living systems is easily rationalized in terms of thermodynamics, the origin of
such living systems is quite another matter."
During biological evolution
after life is established, the basic life-allowing
mechanisms already exist, which allows life to continue with inheritance-replication
that is adequate (but not perfect) through many generations, and during these
generations the mechanisms can increase in variety and complexity through
a neo-Darwinian "ratcheting process" that includes, but is not
limited to, mutation and selection. But even though an evolutionary
increase in biological complexity is compatible with the Second Law, scientists
should still ask "What types of complexity can be produced, in what
amounts, and how quickly?"
In chemical evolution the
basic mechanisms do not exist (thus
life cannot exist) so the mechanisms must be produced (so life
can exist). For a variety of reasons, producing life seems
much more difficult than maintaining life and increasing its diversity & complexity.
Typically, young-earth creationists
use the Second Law of Thermodynamics to criticize ALL evolution, even though
arguments against two types (astronomical and biological) don't seem valid.
Defenders of evolution correctly
claim that an external source of energy can allow a decrease of entropy within
an open system during any type of evolution. But appeals to an inflow
of energy don't address the important difference between chemical evolution
and biological evolution, between producing a
coupling mechanism (in the first generation of life) and then maintaining it
(through succeeding generations). Even though most thermo-based arguments
are wrong, the questions in this page are scientifically interesting and currently
unanswered.
Should scientists consider all possibilities? All
current theories for a natural chemical
evolution from nonlife to life seem implausible, because what is necessary
(for life) seems greater than what is possible (by undirected natural process). Is
it rational for scientists to consider the possibility that carbon-based life
on earth did not originate by undirected natural process, but was the result
of design-directed action? The certainty of "proof" is impossible
because we can never propose and test all possibilities for non-design. But
could we develop a logically justified confidence that our search has been thorough
yet futile, and no promising possibilities remain unexplored?
What are the possibilities? Perhaps a feature, such
as the first life, was produced by undirected natural process that: • did
occur even though it was extremely improbable (so we should reject it as a scientifically
plausible explanation), or • would be improbable in a universe but
was highly probable because we live in a multiverse; or
did occur and was reasonably probable and can be described in a naturalistic
theory that • is currently known (even if this theory currently seems
inadequate) or • will be known in the future, or • will
never be known because the natural process was too complex or unfamiliar for
us to pro pose. Or maybe the feature was produced by design-directed
action, by: • natural design and construction, or • supernatural
design and creation. Should scientists ignore the last two possibilities? .....
What might happen in the future of science? We can try to predict improvements in current theories and inventions of new theories, by using current knowledge (*) plus creative thinking (to imagine what could be) and critical thinking (to predict what is probable in reality, not just possible in our imaginations) so we can avoid the extremes of insisting that "nothing new will happen" or "anything could happen." .....
If the current evidence-and-logic is not
conclusive, maybe saying "no conclusion" is the best conclusion. Instead
of thinking it's necessary to "declare a winner," can we just say "we're
not sure at this time" and continue searching, with a humble open-minded
attitude, in our efforts to learn more?
Should we ask the question? Imagine a "super
science" constructed by trillions of super-intelligent space aliens who
have studied biochemistry for billions of years, have explored the universe searching
for life and environments for producing it, but have not yet constructed a plausible
theory for a natural origin of life. Even in this situation a denial of
design would be possible, but would it be rational?
Compared with this imaginary super-science, in the near
future the actual state of human knowledge will remain much less advanced. For
awhile, scientists will continue to disagree about the plausibility of design,
but this is healthy for science when it stimulates thinking and discussions between
advocates for different points of view. Proof is impossible in science,
and it can be difficult to confidently answer the question, "Was
design-action involved in producing this feature?" Although it should
be easier to decide, "Should we ask the question?", there are
also vigorous arguments about this, as you'll see in Sections 7C and 7D.
For judging the depth
of commitment to naturalism — an assumption
that everything in the history of nature happened by natural process — the
origin of life makes a fascinating test-case. To see why, let's compare
three characteristics of chemical evolution and biological evolution.
• Scientific Support? Current
theories about chemical evolution seem highly implausible, so the
scientific support is very weak. But support is much stronger
(*) for biological evolution,
for a neo-Darwinian development of biocomplexity and biodiversity. * the
scientific support is stronger, but is usually overestimated due
to a shifting of support [that is described in the full page]
• Unifying Function? Most
scientists and educators think biological evolution — but not chemical
evolution — plays an important unifying role in biology.
• Worldview Function? Both
types of evolution are necessary for a worldview of naturalism, for a
universe with a natural total evolution (astronomical,
chemical, and biological), with only normal-appearing natural process
throughout the entire history of nature.
Worldview Asymmetry: If
a natural origin of life (of any type, anywhere in the universe) is impossible,
this would be devastating for the worldview of an atheist, deist, or rigid
agnostic. But either way — with or without a natural origin of
life — is fine
for Christians, including me, as explained in my FAQ
for Creation, Evolution, and Intelligent Design (conclusion of 5B,
plus 5C) and No Proof for the
Existence and Activities of God? Why isn't God more obvious?
When we look at the origin of
life, interesting questions arise from an interesting combination, because
chemical evolution
• is not supported by a logical
evaluation of evidence,
• and is not important for unifying
biological science,
• but is essential for a "no miracles" naturalism.
This is an opportunity for
scientific humility about naturalism. Is the response a humble acknowledgment
that maybe life did not begin by natural process, so maybe naturalism is
wrong? No, instead there are confident statements (by individuals
and organizations, in textbooks and websites) claiming that chemical evolution
definitely did produce life, even though we don't yet know the details
of how this happened.
For example, here are scientists — who
are speaking "in the
name of science" for a prestigious organization — making a claim
that is confident but is not scientifically justifiable:
Although a natural origin
of life by chemical evolution seems implausible, the National Academy
of Sciences confidently asserts (in Science and Creationism, 1999)
that "For those who are studying the origin
of life, the question is no longer whether life could have originated
by chemical processes involving nonbiological components. The
question instead has become which of many pathways might have been
followed to produce the first cells." This confidence
in the power of natural process doesn't seem consistent with the
scientific evidence, so why does the NAS make the claim? Maybe
they are influenced by an assumption, which is not based on science,
that everything in the history of nature happened due to natural
causes.
As explained briefly above, my links-page about Origin of Life: Abiogenesis by Chemical Evolution? — which contains overview-summaries of the main ideas, plus links to pages where you can explore these ideas in more depth — is written by me as an editor (for the "Whole-Person Education" part of the website of the American Scientific Affiliation) and my goal as editor is to describe a wide range of views accurately. By contrast, in the four pages above (about science, thermodynamics, methodology, philosophy) I'm writing as an author, and my goal is to describe my own views and persuasively argue for them.
I'll let you, as a reader, evaluate what I've written and then decide how neutral I've been as an editor (I recognize that I'm not totally unbiased, but I have tried to be fair when writing my descriptions, and in linking to the best pages I could find by advocates of each view) and how persuasive I've been as an author.
Here are excerpts from the introduction in the links-page:
How did life begin? What was the origin
of the first carbon-based life on earth?
Scientists are proposing various theories for a natural origin
of life by a process of abiogenesis (a non-biological
production of life) that can be viewed as a chemical
evolution from non-life to life. ..... [snip] .....
Before looking at web-pages with proposals
(and criticisms, as in claims for Intelligent Design) for various
scientific theories about a natural origin of life, let's get a "big
picture overview" of
some problems and possible solutions: .....
This website for Whole-Person Education has TWO KINDS OF LINKS:
an ITALICIZED LINK keeps you inside a page, moving you to another part of it, and a NON-ITALICIZED LINK opens another page. Both keep everything inside this window, so your browser's BACK-button will always take you back to where you were. |
this page is
http://www.asa3.org/ASA/education/origins/cheme-cr.htm
all pages copyright © by Craig Rusbult, all rights reserved